One step forward and two steps back is how one warrior in the District’s fight for budget autonomy characterized recent federal action.

While the Government Accountability Office on Thursday dealt a blow to D.C.’s effort to unchain its local budget from the congressional appropriations process, declaring a local budget autonomy law null, advocates are gaining strength in the Senate.

Sen. Mark Begich, D-Alaska, an appropriator and key player on D.C. issues, is the latest to throw his backing behind congressional action to free the District’s local tax dollars from Congress’ grip.

Begich declared himself a “supporter of budget autonomy,” saying Thursday he thinks the perennial issue is “important” and that he is “anxious to work on preparing something that we can bring forward.”

It was rosy news for D.C. shadow Sen. Paul Strauss, who has no vote in Congress and plays the role of elected lobbyist for the District. Just an hour before, he had been sifting through the GAO’s 12-page opinion, requested by a Republican on the House Appropriations Committee, that concludes provisions amending the budget process in the Home Rule Act have “no legal effect.”

Like other local supporters, Strauss questioned the GAO’s argument that the new budget procedure would violate the federal Antideficiency Act.

D.C. Council Chairman Phil Mendelson, an architect of the legislation, maintains that the bill adopted unanimously by the council in December 2012, then signed by a skeptical Mayor Vincent Gray and overwhelmingly approved by 83 percent of voters in an April 2013 election is “legal, right and proper.”

That opinion is at odds, however, with D.C. Attorney General Irvin B. Nathan, who has always doubted the legal soundness of the radical, grass-roots approach to changing the budget process.

“We are gratified that the GAO has recognized that our legal assessment was correct,” Nathan said in a statement. “We continue to regret that the citizens were led in the referendum to believe that their votes would alter the federally prescribed budget process, but believe the Congress should give effect to the strongly voiced opinion of our citizens that budget autonomy is fair and just and should be accorded to the District.”

DC Vote Executive Director Kimberly Perry was having none of such sentiment. In a release on Friday, she said budget autonomy “is the law unless Congress enacts legislation signed by the President amending it, or a court overturns it.”

“Without either of those actions,” Perry said, “D.C. officials are required to abide by the Charter Amendment.”

Strauss called Begich’s support “an encouraging step forward.” He told CQ Roll Call, “We can resolve this once and for all when Congress gets on board.”

One of the District’s greatest congressional allies, former Rep. Tom Davis, R-Va., returned to Capitol Hill on Thursday and rallied support.

Begich convened the D.C.-focused subcommittee of the Senate Homeland Security and Governmental Affairs Committee to talk about the impacts of federal government shutdowns on the District, but Davis and other witnesses focused on the city’s need for budget autonomy.

Davis, who helped establish the D.C. Financial Control Board and pushed D.C. voting rights during his 14-year tenure in the House, testified that the city’s growing tax base, surplus of revenue and good credit record prove “the need for congressional micro-management is no longer present, as the city has shown itself to be a responsible steward of its own destiny.”